A crude type of disappearing ink is based on the following endothermic equilibrium:
(colorless) [Co(H2O)6]Cl2 (aq) ⇌ [CoCl2(H2O)4] (aq) + 2 H2O (l) (blue)
If the reactant solution is used to write on a piece of paper and the paper is allowed to partially dry, what can be done to bring out the colored handwriting?
A) decrease the volume
B) put the paper in an oven
C) add water
D) put the paper in a freezer